The major objectives of the study are: 1. A correlation between the chromosomal findings of early bladder lesions, primarily papillary tumors, with their cytologic picture and clinical course. 2. A correlation of the karyotypic picture in advanced cancer of the bladder with response to therapy and clinical course, e.g., sensitivity to X-ray or chemotherapy, metastases, etc. 3. The possible incidence of a missing Y-chromosome in normal and cancerous bladder tissues. To-date, we have examined karyotypically 6 benign bladder tumors, 29 papillary cancers and 54 invasive cancers. The chromosomal findings indicate that they can be very useful, and sometimes crucial, in the evaluation of the behavior of bladder tumors, particularly papillary ones.